Transparency is the important conversion difference
The downloadable 10,962-byte WebP original has transparent areas around and inside a green frame. The JPEG output uses white in those areas because JPEG cannot store an alpha channel. This is deliberate flattening, not a broken download. If you need to place the image over another background, retain WebP or choose PNG instead of JPG.
Download both files and view them against a colored background to check that difference. The example uses a still graphic. This tool does not preserve WebP animation; it is not an animation-to-JPEG sequence exporter.
A reproducible conversion result
Measured with the actual ExactKB compressor in Chrome 155.0.8059.84 on macOS, using decimal units, automatic dimensions and no size preset. Encoder percentages are settings, not measured detail retention. Results vary with the image and browser. Files are synthetic, contain no customer images, and are available below so you can reproduce the comparison.
Download the original test file. Select JPG, the 100 KB target, decimal units and Automatic dimensions. The original is 1200×800 pixels.
On a narrow screen, scroll the results table sideways to see all columns.
| Input / target | Output bytes | Output pixels | Encoder setting | Inspect file |
|---|---|---|---|---|
| Transparent WebP / 100 decimal KB / JPG | 30,950 | 1200×800 | 95% | Download output |
This conversion increased the file from 10,962 to 30,950 bytes. JPEG is useful here for format compatibility; switching formats does not always reduce bytes.
Conversion is not a filename change
Download the result as a new image and reopen it. Changing an extension from .webp to .jpg does not perform conversion. Compare orientation, bytes and output dimensions. A small JPEG might retain all dimensions at the highest tested setting; the tool does not pad it up to your cap. A large image can instead shrink. The 100 KB target is only a starting point: select the actual limit and format your destination permits.
JPG output is lossy; re-encoding an already lossy WebP may add artifacts. Start from the highest-quality source you have. Keep your original before trying another target.
Compare image quality · Understand the 100 KB byte limit · Local processing and privacy